Underground mining of mineral ores, such as coal and hard and soft rock mining requires the widespread use of drilling. Roof bolting is a practical method employed in most coal and other mines. Roof bolts are used in underground mining operations to anchor a tunnel roof, thus preventing it from falling. This is achieved by first drilling a suitably sized hole into the roof that penetrates several rock layers. A ribbed rod covered with resin is inserted into the hole while a washer/nut assembly remains on the outside. The tensile strength of the rod prevents the roof from collapsing. Clamp assemblies are commonly used to guide drill rods and roof bolts in underground mines in order to prevent a whipping action when drilling into roof strata.
Clamp assemblies commonly used in the art comprise clamp arms which in an open position are configured to receive a roof bolt or drill rod. As an operator advances the drill rod or roof bolt between the clamp arms, their fingers may get caught between the exposed clamp arms, potentially resulting in serious injury to the operator.
A clamp assembly having clamp arms which are enclosed in a housing is therefore advantageous as it protects an operator from potentially serious injury and prevents whipping action.